Two speed step motor driving apparatus for copying machines

Abstract

A pulse motor driving apparatus for the optical unit in a copying machine includes an excitation phase designating circuit for designating phase windings alternately from one phase to two phases and from two phases to one phase at the time of original scanning or forward rotation, and also designating the phase windings in pairs with every two phases at the time of return of the optical unit or reverse rotation. A drive circuit supplies drive pulses successively to the phase windings designated by the excitation phase designating circuit to rotate a pulse motor faster at the time of reverse rotation than at the time of forward rotation.

What is claimed is: 
     
       1. An apparatus for driving a pulse motor provided with a plurality of windings, said pulse motor being used for scanning in a copying machine, said apparatus comprising: excitation phase designating means for selectively setting a document scanning mode and a return mode designating the phase windings alternately from one phase to two phases and from two phases to one phase in the document scanning mode, and successively designating the phase windings in pairs with every two phases in the return mode, the pulse motor being rotated faster in the return mode than the document scanning mode; and   drive circuit means for suplying a drive pulse and drive pulses alternately to the one phase winding and two phase windings designated by the excitation phase designating means in the document scanning mode, and supplying drive pulses to the two phase windings designating by the excitation phase designating means in the return mode.   
     
     
       2. A pulse motor driving apparatus according to claim 1, wherein the excitation phase designating means comprises means for setting a stop mode after the return mode, and designating only one phase winding in the stop mode. 
     
     
       3. A pulse motor driving apparaus according to claim 1, wherein the excitation phase designating means has means for storing phase changeover timing data and timer means for generating a phase changeover signal at an excitation time set in response to the phase changeover timing data applied from the storing means. 
     
     
       4. A pulse motor driving apparatus according to claim 3, wherein the storing means stores the phase changeover timing data which change phase changeover timings successively. 
     
     
       5. A pulse motor driving apparatus according to claim 3, wherein, responsive to clock pulses, the timer means counts down the excitation time set by the timing data, and generates the phase changeover signal when the count of said timer means becomes zero. 
     
     
       6. A pulse motor driving apparatus according to claim 1, wherein the pulse motor is to drive the optical unit in the copying machine.